Questions tagged [integer]
For challenges involving the manipulation of integers.
310
questions
16
votes
14answers
845 views
Make a Rectangle from a Triangle
You can depict a triangular number, T(N), by writing one 1 on a line, then two 2's on the line below, then three 3's on the line below that, and so on until N N's. You end up with a triangle of T(N) ...
23
votes
9answers
624 views
Maintain diagonal symmetry when placing N items on a square grid
Write a program that takes in two non-negative integers S and N in that order. S represents the side length of a square grid of . characters. N represents the ...
15
votes
14answers
1k views
Generating generating expressions for sequences
(yes, "generating generating" in the title is correct :) )
Context
In middle (?) school we are taught about sequences and, in particular, we are taught about linear sequences where the ...
23
votes
21answers
2k views
Four distinct 8-bit integers
Submit a well-formed program or function with usual I/O rules which satisfy the input, output, and algorithm conditions below. Shortest submission (in bytes) wins. As always, standard loopholes are ...
12
votes
4answers
400 views
Solving the water bucket riddle!
Context
The water buckets riddle or the water jugs riddle is a simple riddle that can be enunciated in a rather general form as:
Given \$n > 0\$ positive integers \$a_1, a_2, \cdots, a_n\$ ...
18
votes
22answers
2k views
17
votes
20answers
2k views
All aboard the factorial train
The system
Assume the Earth is flat and that it extends infinitely in all directions. Now assume we have one infinitely long train railway and n trains in that ...
28
votes
45answers
4k views
How many petals around the rose
How many petals around the rose
How many petals around the rose is a dice game you can play with your friends. Similar to "can I join the music box", there is a person that knows how the game works ...
15
votes
23answers
2k views
Summing a sub-square of a quarter of an infinite chessboard
Description of the problem
Imagine a quarter of an infinite chessboard, as in a square grid, extending up and right, so that you can see the lower left corner. Place a 0 in there. Now for every other ...
9
votes
5answers
477 views
Computing a specific coefficient in a quotient of polynomials
Context
After "Computing a specific coefficient in a product of polynomials", asking you to compute a specific coefficient of polynomial multiplication, I wish to create a "mirror" challenge, asking ...
34
votes
45answers
3k views
(RGS 1/5) Binary multiples
A binary multiple of a positive integer k is a positive integer n such that n is written ...
38
votes
13answers
3k views
2
votes
5answers
164 views
Shift the digits [closed]
Here, x (supplied as input) and n (the result of your computation) are both positive integers. n * x = n shifted. Find n.
Here's an example of shifting:
...
12
votes
9answers
1k views
Integer Logarithm
Objective
Take \$a \in ℤ_{>1}\$ and \$b \in ℤ_+\$ as inputs. Write a function \$f\$ such that:
$$
f(a,b) =
\left\{
\begin{array}{ll}
\log_ab & \quad \text{if} \space \log_ab \in ℚ ...
36
votes
37answers
8k views
Is this a triangle?
Task
Write a function/program that, given three positive integers a, b and c, prints a ...
22
votes
22answers
2k views
Mountain range numbers
Mountain range number
A number is a mountain range number if the inequalities satisfied by their consecutive digits alternate. In a way, looking at the number's digits should exhibit a ...
20
votes
24answers
2k views
Power-Ending Patterns
When you look at the last decimal digit of each power of a non-negative integer a repeating pattern forms. For example, 3:
...
14
votes
14answers
890 views
Computing a specific coefficient in a product of polynomials
Generator functions
This gives the context for why this challenge came to life. Feel free to ignore.
Generator functions are a nice way of encoding the solution to a problem of combinatorics. You ...
31
votes
5answers
2k views
Make The Finest Magic Code Square
In math a magic square is an N×N grid of numbers from 1 to N2 such that every row, column, and diagonal sums to the same total. For example here's a 3×3 magic square:
In this challenge we'...
4
votes
15answers
2k views
Move my liquid to make me equal
You are given 4 positive integers: volume of the first container (v1), volume of the second container (v2), volume of the liquid ...
19
votes
9answers
1k views
Proportion of self-avoiding walks on a square lattice
The challenge
Given a positive integer N, compute the proportion of N-step walks on a plane that don't intersect themselves.
...
21
votes
38answers
4k views
Round up my number
Sandbox
Given two positive integers a and b, return the smallest multiple of b that is greater than or equal to a.
Examples
Definitions: true = ...
16
votes
16answers
1k views
Find the length of a number's “base-jumping” path
Consider a positive integer N written in base b. A sequence is generated from this number by finding the largest digit ...
24
votes
8answers
2k views
Inverse Look-and-Say
Background
The Look and Say Sequence is built up by reading off the digits of previous entries in the sequence, counting the number of digits in groups of the same digit. For example:
...
1
vote
0answers
72 views
Making Fibonacci Cry [duplicate]
Introduction
The Fibonacci sequence is a mathematical sequence in which each term is the sum of the \$2\$ terms before it; the first two terms are \$0\$ and \$1\$. The first few terms are \$0, 1, 1, ...
1
vote
20answers
470 views
Quine in Bytes, not Characters [duplicate]
Introduction
A quine is a program that takes no input and produces a copy of its own source code as output. Writing a quine is a standard test of a programming language. Most quines operate using ...
19
votes
25answers
4k views
Visualize a large int
Convert a large int (e. g. 1234567890) into a string containing the usual decimal prefixes k, M, G, T, etc. for kilo, mega, giga, tera, etc. The result shall be groups of three digits, interspersed ...
13
votes
35answers
2k views
Determine the Winner of a Game of Australian Football
In Australian Football, goals are worth 6 points and behinds are worth 1 point. Scores may include the number of goals and behinds, as well as the total score. Given the number of goals and behinds ...
32
votes
29answers
5k views
Double it your way
There have been a couple of challenges involving doubling source code: here and here. The task we have here is a bit harder, but should be doable in almost every language.
In this challenge, you will ...
28
votes
17answers
4k views
Infinitely many primes
Since Euclid, we have known that there are infinitely many primes. The argument is by contradiction: If there are only finitely many, let's say \$p_1,p_2,...,p_n\$, then surely \$m:=p_1\cdot p_2\cdot.....
24
votes
24answers
5k views
Count the number of triangles
Given a list of positive integers, find the number of triangles we can form such that their side lengths are represented by three distinct entries of the input list.
(Inspiration comes from CR.)
...
19
votes
30answers
2k views
Numbers Decrease while Letters Increase
Randomly inspired by Numbers Increase While Letters Decrease
Given a list of mixed letters and integers (e.g., ['a', 2, 3, 'b']) increase the letters by one ...
27
votes
30answers
3k views
Output with the same length always
With challenges like Output with the same length as the code and Create output twice the length of the code, I thought of a separate, but similar challenge.
The task is to produce an output. It can ...
14
votes
1answer
311 views
Decompose Commutators
A theorem in this paper1 states that every integral n-by-n matrix M over the integers with trace M = 0 is a commutator, that means there are two integral matrices A,B of the same size ...
35
votes
35answers
5k views
Repeated! Factorials!
Not to be confused with Find the factorial!
Introduction
The factorial of an integer n can be calculated by
$$n!=n\times(n-1)\times(n-2)\times(...)\times2\times1$$...
29
votes
29answers
4k views
Inverse Colombian Function
Let's define a sequence: The n digit summing sequence (n-DSS) is a sequence that starts with n. If the last number was k, then the next number is k + digit-sum(k). Here are the first few n-DSS:
...
6
votes
4answers
455 views
Find X,Y,Z coordinates from index
Introduction
I began studying the Collatz Conjecture
And noticed these patterns;
0,1,2,2,3,3...A055086, and 0,1,2,0,3,1...A082375,
in the numbers that go to 1 in one odd step,
5,10,20,21,40,42......
24
votes
24answers
3k views
Robbers: The Hidden OEIS Substring
This is a Cops and Robbers challenge. This is the robber's thread. The cop's thread is here.
The cops will pick any sequence from the OEIS, and write a program p that prints the first integer from ...
38
votes
27answers
4k views
Cops: The Hidden OEIS Substring
This is a Cops and Robbers challenge. This is the cop's thread. The robber's thread is here.
As a cop, you must pick any sequence from the OEIS, and write a program p that prints the first integer ...
27
votes
54answers
6k views
Integer Lists of Noah
Introduction:
I think we've all heard of it, but here a very brief summary: Noah gathered two of every species of animal on the planet, male and female, to save in his Ark during a great flood. The ...
3
votes
3answers
119 views
Sum of multiples of powers of ten of an integer [duplicate]
Write a function to produce, for a non-negative integer, a string containing a sum of terms according to the following:
...
-6
votes
4answers
221 views
Is this number a palindrome? [closed]
Input
A single integer in your language's preferred format, e.g int or an array of digits are all acceptable.
Output
A truthy or falsely value, depending on ...
38
votes
31answers
14k views
Do the 26 richest billionaires own as much wealth as the poorest 3.8 billion people?
Introduction:
A few days ago I read this post with the same title when I came across it in the HNQ. In this question it is being discussed if the claim of president-candidate Bernie Sanders, who ...
45
votes
12answers
3k views
Prime parity peregrination
The purpose of this challenge is to graphically depict a walk on the plane, where the direction of each step \$k\$ is determined by the primality of \$k\$ and the parity of its binary expansion. ...
7
votes
0answers
201 views
Fastest way to iterate over sublattice of discrete lattice
I need to construct a functor that iterates over the linear representation of a sub-lattice of size \$d_x,d_y,d_z,d_q\$ embedded in a lattice of size \$n_x,n_y,n_z,n_q\$. The sub-lattice corner is ...
22
votes
6answers
1k views
Subtract the Folded Matrix
Challenge:
Given an NxN matrix where \$N\geq2\$ and one of eight distinct 'folding options', output a 2D array/list with the subtracted values.
The eight folding options are: left-to-right; right-to-...
12
votes
6answers
926 views
Group Integers by Originality
Introduction:
I collect twisty puzzles. Most twisty puzzles are produced and sold by Chinese companies. Most well-known companies ask permission from puzzle designers to produce their designs and ...
20
votes
22answers
2k views
Rotated Position of Integers
Challenge:
Input:
A sorted list of positive integers.
Output:
The amount of integers which are still at the exact same index, after rotating the digits in each integer its index amount of times ...
8
votes
4answers
614 views
Leading and Suffering Numbers
Introduction:
In Dutch, the words leading and suffering, being 'leiden' and 'lijden' respectively, are pronounced the same way. One is written with a "short ei", and one with a "long ij", as we ...
20
votes
9answers
1k views
Warped chessboard
This challenge is about building a chessboard in which the square size, instead of being constant across the board, follows a certain non-decreasing sequence, as described below.
The board is defined ...
